A study has been carried out on the base‐catalyzed polymerization of octamethylcyclotetrasiloxane (D4) in tetrahydrofuran solution by means of various anionic initiators. These included potassium hydroxide, sodium and potassium metal and sodium and potassium naphthalene. Tetrahydrofuran was found to have a very marked accelerating effect on the polymerization rate, presumably by increasing the concentration of the silanolate anions. The rates obtained with the potassium metal and potassium naphthalene were even faster than for the KOH, permitting room temperature polymerization in a few hours. The polymerization temperature was not found to affect the equilibrium conversion of monomer to polymer, indicating very similar activation energies for propagation and depropagation. For polymerizations catalyzed by potassium naphthalene, two molecules of catalyst were found to be consumed per chain formed, with one dihydronaphthalene structure included in the chain.
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Morton et al. (1964) studied this question.
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